PyPy
lastmod 2018-08-17created 2017-01-243 edits
PyPy is a Python implementation written in the Python programming language itself, for flexibility and ease of experimentation. One of the project's goals is to make PyPy's optimized Python implementation faster than the current C implementation. PyPy itself is implemented in RPython, a subset of the Python language.
PyPy includes a just-in-time compiler that automatically translates Python code into machine code or other low-level languages. What is unusual is that the JIT compiler itself is generated automatically by a JIT compiler generator — by analyzing PyPy's RPython code.
It depends on the benchmark, but since version 1.4 PyPy has performed better than CPython.
For example, PyPy 1.4 is the first version in which the code that compiles PyPy itself runs faster on PyPy than on CPython.